health check doc for single layer

docs/en/solution-templates/single-layer-web-application/health-check-configuration.md

@@ -10,3 +10,106 @@
 }
 ```
 
+Health Check is a feature that allows applications to monitor their health and diagnose potential issues. The single-layer solution template comes with pre-configured Health Check system.
+
+In the single-layer solution template, Health Check configuration is applied in the following cases:
+
+- When [MVC](https://abp.io/docs/latest/solution-templates/single-layer-web-application/web-applications#mvc) is selected as the web application type.
+- When [Blazor Server](https://abp.io/docs/latest/solution-templates/single-layer-web-application/web-applications#blazor-server) is selected as the web application type.
+- When [Angular](https://abp.io/docs/latest/solution-templates/single-layer-web-application/web-applications#angular) is selected as the web application type (configured at the backend).
+- When [No UI](https://abp.io/docs/latest/solution-templates/single-layer-web-application/web-applications#no-ui) is selected as the web application type (configured at the backend).
+
+### Configuration in `HealthChecksBuilderExtensions.cs`
+
+Health Checks are configured in the `HealthChecksBuilderExtensions` class. This class extends `IServiceCollection` to register health check services and configure health check UI endpoints.
+
+#### Default Configuration
+
+The default setup is as follows:
+
+```csharp
+using HealthChecks.UI.Client;
+using Microsoft.AspNetCore.Diagnostics.HealthChecks;
+
+namespace MyCompanyName.MyProjectName.HealthChecks;
+
+public static class HealthChecksBuilderExtensions
+{
+    public static void AddMyProjectNameHealthChecks(this IServiceCollection services)
+    {
+        // Add your health checks here
+        var healthChecksBuilder = services.AddHealthChecks();
+        healthChecksBuilder.AddCheck<MyProjectNameDatabaseCheck>("MyProjectName DbContext Check", tags: new string[] { "database" });
+
+        // Read configuration for health check URL
+        var configuration = services.GetConfiguration();
+        var healthCheckUrl = configuration["App:HealthCheckUrl"] ?? "/health-status";
+        
+        services.ConfigureHealthCheckEndpoint(healthCheckUrl);
+
+        // Configure HealthChecks UI
+        var healthChecksUiBuilder = services.AddHealthChecksUI(settings =>
+        {
+            settings.AddHealthCheckEndpoint("MyProjectName Health Status", healthCheckUrl);
+        });
+
+        // Set HealthCheck UI storage
+        healthChecksUiBuilder.AddInMemoryStorage();
+
+        services.MapHealthChecksUiEndpoints(options =>
+        {
+            options.UIPath = "/health-ui";
+            options.ApiPath = "/health-api";
+        });
+    }
+
+    private static IServiceCollection ConfigureHealthCheckEndpoint(this IServiceCollection services, string path)
+    {
+       ....
+    }
+
+    private static IServiceCollection MapHealthChecksUiEndpoints(this IServiceCollection services, Action<global::HealthChecks.UI.Configuration.Options>? setupOption = null)
+    {
+       ....
+    }
+}
+```
+
+### Database Health Check Implementation
+
+The `MyProjectNameDatabaseCheck` class is a custom implementation of a health check that verifies database connectivity using `IIdentityRoleRepository`.
+
+```csharp
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Diagnostics.HealthChecks;
+using Volo.Abp.DependencyInjection;
+using Volo.Abp.Identity;
+
+namespace MyCompanyName.MyProjectName.HealthChecks;
+
+public class MyProjectNameDatabaseCheck : IHealthCheck, ITransientDependency
+{
+    protected readonly IIdentityRoleRepository IdentityRoleRepository;
+
+    public MyProjectNameDatabaseCheck(IIdentityRoleRepository identityRoleRepository)
+    {
+        IdentityRoleRepository = identityRoleRepository;
+    }
+
+    public async Task<HealthCheckResult> CheckHealthAsync(HealthCheckContext context, CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            await IdentityRoleRepository.GetListAsync(sorting: nameof(IdentityRole.Id), maxResultCount: 1, cancellationToken: cancellationToken);
+            return HealthCheckResult.Healthy($"Could connect to database and get record.");
+        }
+        catch (Exception e)
+        {
+            return HealthCheckResult.Unhealthy($"Error when trying to get database record. ", e);
+        }
+    }
+}
+```
+